The method and apparatus of the present invention is particularly concerned with signature folding in web press printing applications. In such applications a tucker roll carries a sheet or signature edgewise into tangential relation with a jaw roll for gripping of an intermediate portion of the sheet and continued movement with the jaw roll, which effects folding of the sheet about a gripped region. In the folding action the initially leading edge portion is swung about the gripped region toward the trailing edge portion. As higher production speeds are attempted this folding operation results in wrinkling, tearing and like damage to the sheet material, especially to the leading edge portion upon its rearward swinging motion. In particular, the increased operating speeds tend to cause corrugating or wrinkling of the leading edge portions of the sheet, and the slapping of the leading edge sheet portion against the trailing edge sheet portion at high speed can cause creasing, cracking and tearing of the folded material.
While attempts have been made to overcome these high speed operating problems, the attempts have not been satisfactory. The prior art has proposed the use of bristle brushes to constrain the signature sheets to a desired path, and it has been proposed to use mechanical rollers and air pressured bars to overcome these problems, but without satisfactory results. Examples of the known prior art are shown in the following patents:
______________________________________ U.S. Pat. Nos. U.S. Pat. Nos. ______________________________________ 1,979,093 2,211,046 2,211,791 2,659,437 2,775,448 3,032,335 3,228,710 3,758,102 3,843,113 4,036,487 4,073,485 4,113,243 ______________________________________